Congregated with English in special mass bishop conducted (9)
I believe the answer is:
assembled
'congregated' is the definition.
(thesaurus)
'english in special mass bishop conducted' is the wordplay.
'english' becomes 'e' (abbreviation).
'in' is an insertion indicator.
'special' indicates anagramming the letters.
'bishop' becomes 'b' (abbreviation used in chess).
'conducted' becomes 'led' ('lead' can be a synonym of 'conduct'**).
'mass' is an anagram of 'assm'.
'e' placed into 'assm' is 'assem'.
'assem'+'b'+'led'='ASSEMBLED'
'with' acts as a link.
(Other definitions for assembled that I've seen before include "Brought together" , "Collected in one place" , "Came together or put together" , "Convened came together" , "Gathered in one place or put together" .)